Cooling liquid composition

Abstract

To achieve stable cooling performance by preventing occurrence of insoluble components and deposits due to components of hard water contained in cooling water.SOLUTION: A cooling liquid composition contains polycarboxylic acid polyalkylene glycol graft polymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to coolant compositions. [Background technology]

[0002] Due to the hard water contained in the coolant, etc., sediment may occur during use. In order to prevent this precipitation, it has been necessary to use pure water instead of hard water. However, hard water such as tap water has typically been used as a coolant for internal combustion engines, electric vehicles, fuel cell vehicles, etc. Therefore, when coolants diluted with tap water or the like are used, the components contained in the hard water become insoluble or precipitates occur over time. Furthermore, compositions containing additives for stabilizing hard water, as disclosed in Patent Documents 1 to 4 below, have been known for use as coolants with the aim of preventing the generation of precipitates.

[0003] Even in the case of coolant compositions containing the above-mentioned conventional components that stabilize water, the hard water components (magnesium and calcium) contained in the water in the coolant may react with the components contained in the coolant or with the carbon dioxide contained therein, resulting in the formation of insoluble components or precipitates. Furthermore, the use of conventional coolants can cause components of the coolant to react with and corrode metal surfaces that come into contact with the coolant. As these insoluble components and sediments circulate through the coolant circuit, they can cause the radiator to clog, overheat, and even coolant leaks. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-514514 [Patent Document 2] Special Publication No. 2020-512440 [Patent Document 3] Japanese Patent Application Publication No. 2019-137839 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-535122 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the object is to prevent the occurrence of insoluble components and precipitates due to hard water components contained in cooling water, thereby achieving stable cooling performance. [Means for solving the problem]

[0006] The coolant composition of the present invention is as follows: 1. A coolant composition containing a polycarboxylic acid polyalkylene glycol graft polymer. [Effects of the Invention]

[0007] The coolant composition containing the polycarboxylic acid polyalkylene glycol graft polymer of the present invention exhibits the effect of not generating insoluble components or precipitates over long-term use, even when diluted with water containing calcium or magnesium, such as tap water or hard water.

[0008] [Polycarboxylic acid polyalkylene glycol graft polymer] The polycarboxylic acid polyalkylene glycol graft polymer in the present invention is an ionic water-soluble polymer. The polycarboxylic acid polyalkylene glycol graft polymer has a structure in which a polyalkylene glycol such as polyethylene glycol, polypropylene glycol, or polyether having ethylene glycol units and propylene glycol units is condensed with the carboxylic acid group of a polymer having a carboxylic acid group. Examples of the polymer having a carboxylic acid group include copolymers of a monomer such as an olefin (e.g., ethylene, propylene, butylene, or butadiene), styrene, an acrylic acid ester, or a methacrylic acid ester with a carboxylic acid group-containing monomer (e.g., acrylic acid, methacrylic acid, or maleic acid), and homopolymers of a monomer having a carboxylic acid group (e.g., acrylic acid, methacrylic acid, or maleic acid). The weight average molecular weight of the polycarboxylic acid polyalkylene glycol graft polymer is not particularly limited, but is preferably 5000 to 400000. This weight average molecular weight is determined as a relative value based on the molecular weight of polystyrene by the GPC method. The concentration of the polycarboxylic acid polyalkylene glycol graft polymer in the coolant is not limited as long as it can exhibit the effects of the present invention, but is preferably 0.001% by weight or more, more preferably 0.005% by weight or more, and even more preferably 0.01% by weight or more. Also, it is preferably 5.0% by weight or less, more preferably 1.0% by weight or less, even more preferably 0.5% by weight or less, and most preferably 0.1% by weight or less. If the concentration is less than 0.001% by weight, the effect of adding the polycarboxylic acid polyalkylene glycol graft polymer may not be fully obtained, and if it exceeds 5.0% by weight, even if more is added, a greater effect may not be obtained.

[0009] [Base] The base of the coolant containing the polycarboxylic acid polyalkylene glycol graft polymer of the present invention is preferably one having antifreeze properties, specifically, one or a mixture of two or more selected from water, alcohols, glycols, and glycol ethers. The water is preferably ion-exchanged water, household tap water, industrial tap water, etc., but it is preferable that it does not contain metals such as alkali metals and alkaline earth metals, halogen elements such as chlorine, etc.

[0010] (Glycols contained in the base material) The glycols include one or more of ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butylene glycol, hexylene glycol, diethylene glycol, triethylene glycol, glycerin, etc., and among these, ethylene glycol or propylene glycol is particularly preferred.

[0011] (Alcohols contained in the base material) The alcohols include, for example, one or more selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol.

[0012] (Glycol ethers contained in the base material) Examples of the glycol ethers include one or more selected from ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and tetraethylene glycol monobutyl ether.

[0013] Among the above bases other than water, ethylene glycol and / or propylene glycol are preferred in terms of ease of handling, price, and availability.

[0014] In addition, trihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, 5-methyl-1,2,4-heptanetriol, or 1,2,6-hexanetriol can also be used. Of the above bases, ethylene glycol and / or propylene glycol are preferred in terms of ease of handling, cost and availability.

[0015] (corrosion inhibitor) A corrosion inhibitor may be added within a range that does not impair the effects of the present invention. Examples of corrosion inhibitors include phosphoric acid and / or its salts, aliphatic carboxylic acids and / or their salts, aromatic carboxylic acids and / or their salts, triazoles, thiazoles, silicates, nitrates, nitrites, borates, tungstates, molybdates, and amine salts, either alone or in combination, sulfur-containing alcohols, sulfur-containing phenols, and amines.

[0016] Examples of phosphoric acid and / or salts thereof include orthophosphoric acid, pyrophosphoric acid, hexametaphosphoric acid, tripolyphosphoric acid, and alkali metal salts thereof, preferably sodium salts and potassium salts.

[0017] Examples of aliphatic carboxylic acids and / or salts thereof include 2-phosphonobutane-1,2,4-tricarboxylic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, 2-ethylhexanoic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanedioic acid, and other dicarboxylic acids, as well as alkali metal salts thereof, preferably sodium salts and potassium salts thereof.

[0018] Examples of aromatic carboxylic acids and / or salts thereof include benzoic acid, toluic acid, para-tert-butylbenzoic acid, phthalic acid, para-methoxybenzoic acid, cinnamic acid, and the like, and alkali metal salts thereof, preferably sodium salts and potassium salts.

[0019] Examples of triazoles include tolyltriazole, benzotriazole, and 4-phenyl-1,2,3-triazole.

[0020] Thiazoles include mercaptobenzothiazole and its alkali metal salts, preferably the sodium and potassium salts.

[0021] Examples of silicates include sodium and potassium metasilicic acid salts, and aqueous solutions of sodium silicate, known as water glass, expressed as Na2O / XSiO2 (where X is 0.5 to 3.3). Examples of nitrates include sodium nitrate and potassium nitrate. Examples of nitrites include sodium nitrite and potassium nitrite. Examples of borates include sodium tetraborate and potassium tetraborate.

[0022] Examples of molybdate salts include sodium molybdate, potassium molybdate, and ammonium molybdate, and examples of amine salts include monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine.

[0023] Examples of sulfur-containing alcohols and sulfur-containing phenols include ethylene oxide adducts of alkylamines, ethylene oxide adducts of alkyldiamines, 2-(methylthio)ethanol, 2-(ethylthio)ethanol, 2-(n-propylthio)ethanol, 2-(isopropylthio)ethanol, 2-(n-butylthio)ethanol, 2-(isobutylthio)ethanol, 2-(phenylthio)ethanol, 2,2'-dithiodiethanol, 2-(2-aminoethylthio)ethanol, 3-(ethylthio)propanol, and 4-(methylthio)butanol. ol, 3-(methylthio)hexanol, 2-thiophenemethanol, 3-thiophenemethanol, 2-thiopheneethanol, 3-thiopheneethanol, 4-(methylthio)-6-(hydroxymethyl)-o-cresol, methionol, DL-methioninol, L-methioninol, thiodiglycol, 6-hydroxy-1,3-benzoxathiol-2-one, 4-(methylthio)benzyl alcohol, 4,4'-thiodiphenol, 3,6-dithia-1,8-octanediol, 3,7-dithia-1,9-nonanediol, and the like.

[0024] Examples of the amines include triethanolamine, diethanolamine, ethanolamine, trimethylamine, and hexamethylenediamine.

[0025] (dye) The coolant composition of the present invention may contain a water-soluble dye, but it is not necessary to contain it. The water-soluble dye that can be used is preferably one that has excellent stability. When the water-soluble dye is blended into the coolant composition of the present invention, the content is preferably 0.0005 to 0.2% by weight, more preferably 0.001 to 0.1% by weight, and even more preferably 0.003 to 0.02% by weight, relative to 100% by weight of the base material of the coolant composition. If the content is less than 0.0005% by weight, it becomes difficult to visually confirm the coloration, and visibility deteriorates.

[0026] (Antifoaming agent) The coolant composition of the present invention may contain an antifoaming agent. The content of such an antifoaming agent in the coolant composition is preferably 0.001 to 1.0% by weight, and more preferably 0.005 to 0.1% by weight.

[0027] Furthermore, the present invention is not limited to the following examples, and can be freely modified and implemented within the scope of the claims.

[0028] (Other additives) As other additives, the pH can be adjusted using a common alkaline substance, preferably a hydroxide of an alkali metal salt such as sodium or potassium. The pH is preferably adjusted to a range of 6.5 to 9.0, more preferably 7.0 to 9.0, and even more preferably 7.4 to 8.5. An antifoaming agent can be added to the coolant composition. The coolant composition does not contain cyclopentane.

[0029] The coolant composition of the present invention may contain, but does not necessarily contain, a pH adjuster such as sodium hydroxide or potassium hydroxide, etc. In addition to the substances mentioned above, antioxidants, rust inhibitors, friction modifiers, corrosion inhibitors, viscosity index improvers, pour point depressants, dispersants / surfactants, antiwear agents, bittering agents, or solid lubricants.

[0030] The coolant composition of the present invention can be obtained by any method, including mixing the necessary components, or by mixing a compound that will produce the components of the present invention upon heating or the like with a base or the like, and then heating the mixture to obtain the components of the present invention. The coolant composition of the present invention can also be used as a coolant composition for electric vehicles, a coolant for internal combustion engines, a fuel cell vehicle, a coolant composition for cooling a fuel cell mounted on a power generation device, a coolant composition for a system having piping or a tank installed in a fuel cell, or a cation exchange resin or an anion exchange resin installed as needed. It should be noted that the present invention is not limited to the following examples. [Example]

[0031] Below, we will list preferred examples of the coolant composition of the present invention and evaluate their performance in comparison with comparative examples. The compositions of the examples and comparative examples shown in Table 1 were all based on ion-exchanged water and ethylene glycol. Viscosity measurements were carried out in accordance with JIS K2283.

[0032] Polycarboxylic acid polyalkylene glycol graft polymer (molecular weight 3,000, viscosity 45±15mPa·s (25℃)) Maleic acid polymer: Weight average molecular weight 937 Sodium polyacrylate (molecular weight 5,500, viscosity 800±200 mPa·s (25°C)) Acrylic acid, maleic acid copolymer sodium salt (molecular weight 50,000, viscosity of 20% aqueous solution 37±7 mPa·s (25°C)) Maleic acid-sulfonic acid-based (viscosity 500±200mPa·s (25℃)) Acrylic acid-sulfonic acid monomer copolymer sodium salt (molecular weight 6,000, viscosity 1,200±200mPa·s (25℃)) Special sodium polycarboxylate (molecular weight 2,000, viscosity 290±60mPa·s (25℃)) Anti-rust additive: a mixture of phosphoric acid, sebacic acid, p-toluic acid, tolyltriazole, and mercaptobenzothiazole

[0033] (Hard water stability test) 50 mL of the coolant composition was mixed with 50 mL of hard water with a calcium ion concentration of 6 mmol / L. This was stored at 90°C for 336 hours. The resulting sample was centrifuged for thorough solid-liquid separation, and the volume of the precipitate was measured.

[0034] (Metal Corrosion Test (Mass Change)) Metal corrosion tests were carried out in accordance with ASTM D1384. Each metal piece was placed in a coolant composition containing 33.3 vol% coolant composition and 66.7 vol% blended water as specified in ASTM D1384, and stored at 88°C for 336 hours. The metal piece was then removed and dried. The mass of the metal piece was measured before and after placement to determine the change in mass per unit surface area of ​​the metal piece. A positive value indicates an increase in mass, and a negative value indicates a decrease in mass.

[0035] (Appearance of test piece) The appearance of each metal piece was thoroughly inspected visually before and after the metal corrosion test to confirm any change in appearance before and after the test.

[0036] [Table 1]

[0037] The examples according to the present invention were excellent in hard water stability, and the corrosiveness (amount of change in mass) of each metal was extremely small. In addition, the metal surfaces were not discolored. In contrast, Comparative Example 1 and Comparative Examples 2 to 7, which did not contain a polycarboxylic acid polyalkylene glycol graft polymer, were inferior in corrosiveness to each metal, and Comparative Examples 3 to 7 caused discoloration of each metal surface after testing.

Claims

[Claim 1] A coolant composition containing a polycarboxylic acid polyalkylene glycol graft polymer.

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